Workshop #1 Flashcards
What structures of mRNA enable & regulate translation?
-5’ cap = enables translation
-3’ polyA tail = regulates translation
What makes up chromatin?
DNA (nucleosomes) + histone proteins
–> 146bp wrapped around 8 histone proteins which have tails
How can chromatin be regulated?
DAIM
-Methylation -> DNA is -ve & CH3+ are +ve - so inc. meth = causes condensation of nucleosomes - as CH3+ bind to histone tails
-Acetylation -> DNA is -ve & acetyl groups (-CO-CH3) are -ve = uncondenses nucleosomes
= both - forms of gene silencing
What is meant by reusing of genes in development?
-All of development depends on right genes being turned on/off at right times & places
–> meaning no. of genes not important - what is important, is how they are used
-How, when, where & how much of a gene is expressed
What controls when a gene is expressed (turned on - from off) in development? -> so what regulates transcription???
By regulatory regions in DNA - with:
-Promotors
-Enhancers
-Silencers
-Insulators
-TFs = regulatory proteins (NOT IN DNA!)
= regulate the transcription
Enhancers VS promoters?
*Enhancer = short region of DNA - a regulatory element - where activators bind to inc. level/likelihood of transcription of a particular gene –> meaning enhancers influence promotor activity - as enhancers always interact with promotors to regulate gene expression
-May not be near transcriptional unit of gene
-Can increase activity of promoter - to increases transcription & thereby - gene expression
*Promoter = DNA sequence where RNA polymerase binds along with basal TFs
-Located near site of transcription initiation of gene (ALWAYS)
-Is a binding site for RNA polymerase (catalyses transcription of gene)
Image to demonstrate enhancers & promotors in action?
-A singular genes can be expressed in different regions of body (reuse)
-> dependent on TFs, time, where, amount = means have different effects (due to interaction with various other proteins present in that region of body)
-Different TFs expressed for gene A to be expressed in brain compared to limb
-Different enhancers for gene A to be expressed in brain compared to limb
–> leads to mRNA expression in brain & in limb separately
Homeotic VS homeobox VS hox?
-Homeotic genes = regulate organ development (patterning)
–> homeotic genes contain homeobox
-Homeobox = (part of homeotic gene) which encodes TFs to activate genes for cell development & differentiation - & are expressed in certain regions of body & determine e.g., presence of wings or legs
-Hox genes = type of homeotic gene & so are members of homeobox TFs superfamily
–> i.e., there are many types of homeotic genes - bilateral animals (e.g., humans) have Hox genes
–> hox genes = have their own homeobox region which encodes the functional DNA-binding domain (i.e., the TF)
What is meant by hox genes exhibiting collinearity?
Order of hox genes along genome/chromosome is reflected/corresponds to the order of their expression domains along anterior-posterior axis of embryo
Where in body is Pax6 expressed & functions - why is this?
-Lens
-Cornea
-Retina
-Neural tube
-Pancreas development
–> regulated by specific enhancers
Role of Pax6 in the eyes?
Induces eye development
What happens when Pax6 is mutated?
-Eyes develop abnormally or not at all
-Humans heterozygous for Pax6 = cause of aniridia
What is the transcriptome?
Sum total of all mRNA molecules expressed from genes of an organism
